No free lunch

In your article about distributed computing using idle computers (15 July, p 11), you didn't mention that a computer used in this way will not enter its power-saving state as it usually does when not in use.

This means that the machine may use up to 100 watts (my guess) more than it would if it was not running these calculations. The cost of running a 100-watt load for a month? Probably something close to the $10 that these companies are talking of offering.

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